Fork insertion amount management support device, forklift using same, and computer program

Abstract

To accurately indicate an insertion state of a fork into a pallet.SOLUTION: The fork insertion amount management support device 101 is used by being attached to the forklift 11 that inserts the forks 32 into the pallet P on which the cargo B is placed and transports the cargo B together with the pallet P. The fork insertion amount management support device 101 includes a device main body 102 and a distance sensor 131 that detects the distance to the pallet P. The device body 102 has a built-in PLC, and calculates a remaining length until the tip end 35E of the fork 32 inserted into one surface side of the pallet P reaches a surface opposite to the one surface of the pallet P, and a protruding length protruding from the opposite surface. The device main body 102 also includes a display device, and is attached to a position visible to the operator sitting on the cab 16. The PLC displays the calculated dimensions of the remaining length and the protruding length as numerical values on the display device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a fork insertion amount management support device, a forklift using the same, and a computer program. [Background technology]

[0002] Forklifts are widely used as a means of moving cargo to a desired location. The cargo is placed on a platform called a pallet, and the forklift inserts its forks into slots on the pallet and then lifts the forks to transport the cargo along with the pallet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 07-101696 [Patent Document 2] Japanese Patent Application Publication No. 09-175798 [Patent Document 3] Japanese Patent Application Laid-Open No. 2001-253699 Summary of the Invention [Problem to be solved by the invention]

[0004] When transporting goods using a forklift, it is important to properly manage the depth of the forks into the pallet, as problems can occur if the forks are inserted too far or too little.

[0005] One problem that can occur when the forks are inserted too far into the pallet is that the tips of the forks may penetrate through the pallet. If multiple items are placed on a pallet, one behind the other, and the tips of the forks penetrate through the pallet, the tips may penetrate into the pallet placed at the back or hit the items placed on top of it. If the forks are raised in this state, the pallet at the back may tilt, causing the load to collapse or damaging the items at the back.

[0006] If the forks are not inserted deep enough into the pallet, the pallet may tilt when lifted by the forks. This can also cause the load to collapse.

[0007] As a method for appropriately managing the insertion amount of a fork into a pallet, configuration examples such as those described in Patent Documents 1 to 3 are known.

[0008] Patent Document 1 describes an invention in which a detector (ultrasonic sensor 4) is provided at the fork mounting portion of a forklift to detect the distance between the fork and the pallet, and when the distance to the pallet falls within an optimum distance range determined from the length of the fork and the depth of the pallet, an alarm is issued by an alarm means (see paragraphs

[0007] -

[0020] of Patent Document 1).

[0009] The notification means issues a notification by turning on a lamp or sounding a buzzer (see paragraphs

[0020] and

[0023] of Patent Document 1).

[0010] Patent Document 2 describes an invention in which a distance detection means (proximity sensor 29) is provided to detect the distance to the pallet or cargo when the forks are inserted into the pallet, and an alarm device issues an alarm when it detects that the insertion amount of the forks has fallen within an appropriate range (see paragraphs

[0008] -

[0017] of Patent Document 2).

[0011] The notification device displays the fork insertion status using a pilot lamp, a liquid crystal display, or other indicator, and notifies the user by a buzzer, chime, voice, or the like (see paragraphs

[0017] -

[0020] of Patent Document 2).

[0012] Patent Document 3 describes an invention in which a fork insertion amount detection means is provided that detects the amount of insertion movement of the fork into the pallet, and displays the amount of insertion movement of the fork into the pallet (see paragraphs

[0005] -

[0014] of Patent Document 3). Examples of the fork insertion amount detection means include a mechanism made up of a detection bar 72 and a detection sensor 76, and a non-contact sensor such as an optical sensor or a magnetic sensor.

[0013] The amount of insertion movement is displayed using a display 8. As a specific example, Patent Document 3 discloses "a lamp that lights up when the amount of insertion of the forks 5 into the pallet 6 reaches a required position" and "a monitor such as a liquid crystal display that continuously displays the insertion position of the forks" (see paragraphs

[0010] and

[0016] of Patent Document 3).

[0014] The inventions described in Patent Documents 1 to 3 have the following problems.

[0015] The inventions described in Patent Documents 1 and 2 issue a notification when the forks are inserted into the optimal position relative to the pallet, but do not issue a notification if the forks are not inserted into the optimal position.

[0016] This means that the forklift operator must stop the forklift as soon as the alarm is issued, which puts them in a very busy position. In some cases, the forklift may not be able to stop immediately after the alarm is issued, which can lead to an overrun. In this case, the forks will not be positioned optimally relative to the pallet.

[0017] The invention described in Patent Document 3 displays the amount of fork insertion movement into the pallet. If a lamp is used as the indicator, it will behave in the same way as the notifications in Patent Documents 1 and 2, and the same problems will arise.

[0018] When a monitor such as a liquid crystal display is used as the display, the fork insertion position is continuously displayed. However, there is no instruction on how to continuously display the fork insertion position, and even if various methods are imagined, it is understood that it is not possible to show the forklift operator how far the forks should be inserted into the pallet.

[0019] As explained above, the inventions described in Patent Documents 1 to 3 have problems in accurately indicating the insertion state of the forks into the pallet and supporting appropriate management of the insertion depth of the forks. Improvements are desired.

[0020] An object of the present disclosure is to accurately indicate the insertion state of the forks into the pallet. [Means for solving the problem]

[0021] a display device mounted in a position visible from the driver's cab of the forklift; a memory unit that stores the length of the pallet in the insertion / removal direction as the pallet length; and a calculation processing unit that calculates the remaining length until the tips of the forks inserted into one side of the pallet reach the side of the pallet opposite to the one side and the protruding length from the opposite side based on the fork length value from the measurement surface of the distance sensor to the tip of the fork, the pallet length value stored in the memory unit, and the distance measured by the distance sensor. The calculation processing unit performs input control to store the pallet length input to the input device in the memory unit, and display control to display the respective dimensions of the remaining length and the protruding length as numerical values ​​on the display device.

[0022] One aspect of a forklift that inserts forks into a pallet carrying a load and transports the load together with the pallet is equipped with the fork insertion amount management support device.

[0023] One aspect of the computer program is loaded into a computer included in a fork insertion amount management support device that is attached to a forklift that inserts forks into a pallet carrying a load and transports the load together with the pallet, and causes the computer to perform the following functions: storing the length of the pallet in a memory unit as a pallet length in response to input from an input device; calculating the remaining length until the tips of the forks inserted into one side of the pallet reach the side of the pallet opposite to the one side and the protruding length from the opposite side, based on the value of the fork length from the measurement surface of a distance sensor that detects the distance between the pallet in the fork insertion / removal direction to the tips of the forks, the pallet length value stored in the memory unit, and the distance measured by the distance sensor; and displaying the numerical values ​​of the remaining length and protruding length on a display device attached in a position visible from the driver's cab of the forklift. [Effects of the Invention]

[0024] The forklift operator can be visually shown the process by which the forks are inserted into the pallet to the appropriate depth, which contributes to optimizing the depth at which the forks are inserted into the pallet. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a perspective view showing a forklift equipped with a fork insertion amount management support device according to an embodiment, together with a pallet carrying a load; [Figure 2] FIG. 1 is a plan view showing a forklift truck in a state where the forks are inserted into a pallet and a load is being transported. [Figure 3] FIG. 1 is a side view showing a forklift truck in a state where the forks are inserted into a pallet and a load is being transported. [Figure 4] 1 is a perspective view of a device body constituting a fork insertion amount management support device according to an embodiment; [Figure 5] FIG. 2 is a block diagram of a fork insertion amount management support device attached to a forklift. [Figure 6] A schematic diagram showing the dimensional relationships of each part, such as pallet length (PL), fork length (L2), and measurement distance (DL). [Figure 7] Schematic diagram showing an example where (A) the measurement surface of the distance sensor and the base of the fork are located in the same plane, and (B) the measurement surface of the distance sensor is offset toward the tip of the fork from the base. [Figure 8] (A) to (D) are schematic diagrams showing the process of inserting a fork into a pallet in chronological order. [Figure 9] 4 is a flowchart showing the flow of processing executed by a PLC provided in the fork insertion amount management support device. [Figure 10] 10 is a flowchart showing the flow of a display process executed in a first operation mode. [Figure 11] 10 is a flowchart showing the flow of a display process executed in a second operation mode. [Figure 12] 5A to 5D are schematic diagrams showing examples of displays on a display device in a first operation mode. [Figure 13] 6A to 6D are schematic diagrams showing examples of displays on the display device in a second operation mode. DETAILED DESCRIPTION OF THE INVENTION

[0026] The fork insertion amount management support device, a forklift using the same, and a computer program according to the embodiment will be described with reference to the accompanying drawings. 1. Forklift (1) Body (2) Fork mechanism (2-1) Lift and tilt operations (2-2) Lift mechanism and tilt mechanism 2. Fork insertion amount management support device (1) External appearance (2) System configuration (3) Principle of support for managing fork insertion amount (3-1) Management support methods (3-2) Calculation processing method (a) Length of each part (b) Arithmetic processing in the first operating mode (c) Arithmetic processing in the second operating mode (4) Management support process for fork insertion amount (4-1) Master setting items (4-2) Processing procedure (a) Home screen (b) Pallet length setting (c) Operation (First operating mode) (Second operating mode) (End of processing) 3. Effects (1) Basic effects (1-1) Effect (1-2) Effects (2) Minus sign (3) Background color (4) Prevention of unnecessary display (5) Two operating modes (6) Distance sensor placement (7) Display and input devices (8) One package 4. Variations

[0027] 1. Forklift As shown in Figures 1 to 3, this embodiment is an example of application to a counterbalance forklift 11. The forklift 11 has a fork mechanism 31 at the front of a vehicle body 12 capable of traveling on four wheels, and a balance weight (not shown) built into the rear. The fork mechanism 31 includes a pair of forks 32 on the left and right. The forklift 11 inserts the forks 32 into an insertion opening S of a pallet P on which a load B is placed, and then lifts the forks 32 to transport the load B together with the pallet P.

[0028] (1) Body Of the four wheels provided on a body 12 of the forklift 11, the two wheels on the front side are drive wheels 13 and the two wheels on the rear side are steering wheels 14.

[0029] The drive wheels 13 are rotated by a power source built into the vehicle body 12 via a transmission (neither of which is shown). The power source may be an internal combustion engine fueled by, for example, diesel, gasoline, LPG (liquefied petroleum gas), or CNG (compressed natural gas), or an electric motor driven by a rechargeable battery. Alternatively, the power source may be a hybrid of an internal combustion engine and an electric motor.

[0030] The steering wheel 14 is steered by a handle 15, and the direction of travel of the forklift 11 is changed by the steering.

[0031] A driver's cab 16 is provided on top of the vehicle body 12. The driver's cab 16 is provided with a seat 17 on which an operator can sit, a handlebar 15 positioned in a position suitable for operation while seated in the seat 17, pedals (not shown), and operating levers (not shown). The pedals include an accelerator pedal, a clutch pedal, and a brake pedal. The operating levers include a gear shift lever, a forward / reverse lever, a lift lever for lifting the fork mechanism 31, and a tilt lever for tilting the fork mechanism 31.

[0032] The forklift 11 is provided with a head guard 18 on top of the vehicle body 12, surrounding the driver's cab 16, to protect the operator from unexpected accidents such as tipping over. The head guard 18 is composed of a pair of left and right beams 19 arched between the front and rear parts of the vehicle body 12, and a roof 20 spanning between the left and right beams 19. The roof 20 is positioned above the head of the operator sitting in the seat 17.

[0033] In this embodiment, the regions of the pair of left and right beams 19 that extend upward from the front portion of the vehicle body 12 are called front pillars 21.

[0034] (2) Fork mechanism (2-1) Lift and tilt operations The fork mechanism 31 has a pair of left and right forks 32 and has a structure for lifting and tilting the forks 32. The pair of forks 32 are arranged parallel to the X-axis direction in FIG. 1 and both extend along the Y-axis direction.

[0035] In FIG. 1, the X-axis direction is a direction perpendicular to the traveling direction of the body 12 of the forklift 11, the Y-axis direction is a direction along the traveling direction of the body 12, and both the X and Y axes are parallel to the ground surface G (see FIG. 3). The Z-axis direction is a direction perpendicular to the ground surface G. In the initial state where no tilting operation is performed, the pair of forks 32 extending along the Y-axis direction are arranged parallel to the ground surface G. In this case, the directions of the X, Y, and Z axes are determined based solely on the ground surface G, rather than on the direction of gravity.

[0036] The lift operation is an operation of raising and lowering the pair of forks 32 in the Z-axis direction. The raising and lowering direction at this time is the Z-axis direction assuming that the forks 32 are not tilted. When the forks 32 are tilted, the raising and lowering direction of the forks 32 is shifted from the Z-axis by the tilt angle.

[0037] The tilting operation is an operation of tilting the Z axis toward the vehicle body 12, thereby changing the angle of the pair of forks 32. The forks 32 tilt so that their tips rise.

[0038] (2-2) Lift mechanism and tilt mechanism The fork mechanism 31 includes a mast 33 attached to the front of the vehicle body 12 and a backrest attached to the mast 33. The pair of forks 32 are fixed to the backrest .

[0039] The mast 33 is a rectangular frame structure that is long in the Z-axis direction and is attached to the vehicle body 12 so as to be rotatable around its lower end. The rotation range of the mast 33 is determined as a range from an upright position along the Z-axis to a position where the upper portion is tilted toward the vehicle body 12 by a predetermined angle. The predetermined angle to which the mast 33 is tilted determines the tilt angle of the fork 32 during tilting operation.

[0040] The backrest 34 is a rectangular frame structure that is attached to the mast 33 so as to be able to rise and fall. The size of the backrest 34 is larger in the X-axis direction than the mast 33 and smaller in the Z-axis direction. The role of the backrest 34 is to receive the cargo B lifted together with the pallet P by the forks 32 and to prevent the cargo B from falling toward the cab 16.

[0041] Another role of the backrest 34 is to raise and lower the pair of forks 32. Since the pair of forks 32 are fixed to the backrest 34, they rise and lower in response to the raising and lowering movement of the backrest 34.

[0042] The pair of forks 32 are bent at a right angle and have claw portions 35 and base portions 36. The claw portions 35 extend along the Y-axis direction, and are inserted from their tip portions 35E into the insertion slots S of the pallet P. The base portions 36 are bent at a right angle from the root portions 35R of the claw portions 35 and are fixed to the backrest 34. The ends of the base portions 36 are folded back to sandwich the backrest 34. In this state, the base portions 36 are fixed to the backrest 34, for example, by bolts.

[0043] The fork mechanism 31 includes a lift cylinder 37 as a drive source for raising and lowering the backrest 34 so as to perform a lifting operation on the forks 32. The lift cylinder 37 is a hydraulic cylinder driven by, for example, an electric pump (not shown), and is attached between the mast 33 and the backrest 34 so that the backrest 34 can be raised and lowered in response to the extension and contraction of a built-in rod (not shown). By controlling the drive of the electric pump to adjust the extension and contraction amount of the rod of the lift cylinder 37, the amount of lifting and lowering of the pair of forks 32 that rise and fall together with the backrest 34 is controlled, and a lifting operation is performed.

[0044] The fork mechanism 31 includes a tilt cylinder 38 as a drive source for rotating the mast 33 to tilt the forks 32. The tilt cylinder 38 is a hydraulic cylinder driven by, for example, an electric pump (not shown), and is attached between the body 12 of the forklift 11 and the mast 33 so that the mast 33 can be swung in response to the extension and retraction of a built-in rod (not shown). By controlling the drive of the electric pump to adjust the extension and retraction amount of the rod of the tilt cylinder 38, the amount of angle variation of the pair of forks 32, which change their angle relative to the Z axis together with the mast 33 and the backrest 34, is controlled, thereby performing the tilt operation.

[0045] Here, a few words will be added about the prongs 35 and base 36 of the fork 32.

[0046] Considering the role of the forks 32, which is to insert them into the pallet P and transport them together with the cargo B, the claws 35 constitute the substance of the forks 32, and the role of the base 36 is merely to fix the forks 32 to the backrest 34 and to fix the claws 35 in the correct position. For this reason, in the present embodiment, the forks 32 may be described as being the same as the claws 35.

[0047] For example, the expression "tip 35E of fork 32" means the tip 35E of claw 35 that constitutes fork 32. The expression "base 35R of fork 32" means the base 35R of claw 35 that constitutes fork 32. The expressions "insertion state, insertion amount, and insertion length of fork 32 relative to pallet P" mean the insertion state, insertion amount, and insertion length of claw 35 relative to pallet P, respectively.

[0048] 2. Fork insertion amount management support device The forklift 11 is equipped with a fork insertion amount management support device 101.

[0049] (1) External appearance The fork insertion amount management support device 101 has a device main body 102 and a distance sensor 131 as hardware resources, and displays the insertion state of the fork 32 into the insertion port S of the pallet P, and performs management support for the fork insertion amount.

[0050] 4, device main body 102 has a typical tablet terminal configuration in which display device 104 is provided on one surface of thin rectangular housing 103, and touch panel 105 is laminated on display screen 104a of display device 104. Touch panel 105 functions as an input device.

[0051] The device main body 102 is configured to be attached to a position where the display screen 104a can be viewed from the driver's cab 16, for example, to the front pillar 21. The device can be attached to the front pillar 21 by any means, such as by using an adapter that can be fixed to the front pillar 21 or by providing a clip that clamps the front pillar 21.

[0052] As shown in Figures 1 to 3, the distance sensor 131 is attached to the body 12 of the forklift 11, and is used to detect the distance between the forks 32 and the pallet P in the insertion / removal direction (Y direction in Figure 1) of the forks 32 relative to the pallet P. Any type of sensor can be used as the distance sensor 131, whether it is optical, ultrasonic, or radio wave type, as long as it has a detectable distance up to the maximum length of the forks 32, for example, about 2 meters, and has the detection performance to detect the pallet P or the cargo B.

[0053] In this embodiment, the distance sensor 131 converts the acquired analog signal into a digital signal and outputs it as a digital signal.

[0054] (2) System configuration 5, the device main body 102 has a built-in computer, PLC 111, that is, a programmable logic controller. The PLC 111 mainly includes a CPU 112 as an arithmetic processing unit that executes various arithmetic processing and centrally controls each unit, and is connected to the CPU 112 via signal lines, control lines, etc., with a memory 113 as a storage unit, an input interface 114, and an output interface 115.

[0055] The memory 113 includes volatile memory such as RAM, as well as non-volatile memory such as flash memory and EEPROM. The volatile memory is used as a work area for temporarily storing variable data. The non-volatile memory stores fixed data such as user programs and system parameters. The fixed data may be backed up by a battery in the volatile memory as needed.

[0056] The touch panel 105 and the distance sensor 131 are connected to the input interface 114. The PLC 111 takes in, into the input interface 114, a digital signal obtained by binarizing the position information on the display screen 104a transmitted from the touch panel 105 and a digital signal obtained by binarizing the distance measurement information transmitted from the distance sensor 131, and provides them for processing in accordance with a user program stored in the memory 113.

[0057] A display device 104, such as a liquid crystal display or an organic EL display, is connected to the output interface 115. The PLC 111 generates a digital signal for displaying a desired image on a display screen 104a of the display device 104, and outputs the signal via the output interface 115 to a driver (not shown) built into the display device 104.

[0058] The PLC 111 can store a user program generated by, for example, a programming support tool 202 installed in a user's personal computer 201 as a computer program 203 in memory 113. In this embodiment, the CPU 112 executes the processes shown in Figures 9 to 11 in accordance with the computer program 203 stored in memory 113. This allows the PLC 111 to realize the behavior of a fork insertion amount management support device 101 using hardware resources.

[0059] The device main body 102 incorporates a power supply unit 116 equipped with a rechargeable battery (not shown), such as a lithium ion battery. The power supply unit 116 supplies power to the PLC 111, the display device 104, the touch panel 105, and the distance sensor 131.

[0060] The device main body 102 has a PLC 111 including a CPU 112 (arithmetic processing unit), a memory 113 (storage unit), an input interface 114, and an output interface 115, a display device 104, a touch panel 105 (input device), and a power supply unit 116 housed within a single housing 103.

[0061] (3) Principle of support for managing fork insertion amount (3-1) Management support methods In this embodiment, the management support for the amount of forks inserted is performed by displaying the insertion status of the forks 32 relative to the pallet P as a numerical value on the display screen 104a of the display device 104. In this case, in this embodiment, two types of operation modes can be performed, which differ in the way in which the insertion status of the forks 32 relative to the pallet P is expressed.

[0062] In the first operation mode, the remaining length RL (see FIG. 8(B)) until the tip ends 35E of the forks 32 inserted into one side of the pallet P reach the side opposite to one side of the pallet P and the protruding length EL (see FIG. 8(D)) from the opposite side are displayed as numerical values ​​and shown to the operator of the forklift 11. In this case, the remaining length RL is displayed as a numerical value without a positive or negative sign, and the protruding length EL is displayed as a numerical value with a negative sign "-". Furthermore, the background color displayed on the display screen 104a is green when displaying the remaining length RL until it reaches 0, and red when displaying the protruding length EL, to alert the operator.

[0063] In the second operation mode, the insertion length IL (see FIG. 8(B)) of the forks 32 relative to the pallet P is displayed numerically and shown to the operator of the forklift 11.

[0064] (3-2) Calculation processing method (a) Length of each part 6, in this embodiment, the length of the claw 35 corresponding to the actual length of the fork 32 is defined as the claw length L1. The claw length L1 is the length from the base 35R of the claw 35 to the tip 35E.

[0065] The distance sensor 131 detects the distance between the pallet P and the fork 32 in the insertion / removal direction (Y direction in FIG. 1). When the length from the measurement surface 131a of the distance sensor 131 to the tip of the fork is defined as the fork length L2, L1=L2 ……(1) 7A, the claw length L1 and the fork length L2 are the same. In this case, if the distance DL measured by the distance sensor 131 is the same as the fork length L2 (= claw length L1), it can be seen that the tip ends 35E of the forks 32 have reached one surface of the pallet P, and the tip ends 35E of the forks 32 and the one surface of the pallet P are positioned in the same plane.

[0066] In contrast, the distance sensor 131 attached to the backrest 34 has a certain thickness in the Y-axis direction in Fig. 1. As shown in Fig. 7(B), it is generally assumed that the thickness dimension of the distance sensor 131 is larger than the thickness dimension of the base 36 of the fork 32. For this reason, when the position of the base 35R of the claw 35 of the fork 32 is taken as the reference position, the measurement surface 131a of the distance sensor 131 is offset toward the tip 35E. In this embodiment, the offset of the measurement surface 131a at this time is treated as a correction error, and this dimension is defined as the offset length L3.

[0067] From the relationship between the lengths L1 to L3 described above, the fork length L2 is: L2 = L1 - L3 ……(2) It can be calculated using the formula:

[0068] In this case, if the thickness of the distance sensor 131 is small and does not reach the thickness of the base 36 of the fork 32, the offset length L3 may be treated as a negative value.

[0069] 8(A) to 8(D) are schematic diagrams showing, in time sequence, the process of inserting the forks 32 into the pallet P. The pair of forks 32 faces one side of the pallet P to be transported (see FIG. 8(A)), and as the forklift 11 moves forward, they are inserted into the pallet P (see FIG. 8(B)), and reach the opposite side of the pallet P (see FIG. 8(C)). As the forks 32 move forward further, they penetrate through the opposite side of the pallet P (see FIG. 8(D)).

[0070] Figure 8(B) shows the insertion length IL and remaining length RL of the forks 32 relative to the pallet P. Figure 8(D) shows the protruding length EL of the forks 32 protruding from one surface of the pallet P and the opposite surface.

[0071] (b) Arithmetic processing in the first operating mode The remaining length RL and the protruding length EL can be calculated based on the value of the fork length L2, the value of the pallet length PL which is the depth length of the pallet P, and the distance DL measured by the distance sensor 131.

[0072] The CPU 112 executes two processes to calculate the remaining length RL and the protruding length EL. The first process is to subtract the value of the measured distance DL from the value of the fork length L2 to calculate the insertion length IL of the fork 32 relative to the pallet P. The second process is to subtract the value of the insertion length IL from the value of the pallet length PL to calculate the remaining length RL and the protruding length EL. These two processes are, for example, PL-(L2-DL) ……(3) This can be done by using the formula below and its variants.

[0073] When the solution of equation (3) is a positive value or 0, the CPU 112 interprets it as the remaining length RL, and when it is a negative value, it interprets it as the protruding length EL.

[0074] (c) Arithmetic processing in the second operating mode The insertion length IL of the forks 32 relative to the pallet P can be calculated by subtracting the measured distance DL from the fork length L2, as described in the first operation mode. L2-DL ……(4) This can be done by using the formula below and its variants.

[0075] The CPU 112 calculates the insertion length IL using the calculation formula (4) or a modified version thereof. If the solution is a negative value, it is understood that the forks 32 are not inserted into the pallet P.

[0076] (4) Management support process for fork insertion amount The processing content of the PLC 111 executed to support management of the fork insertion amount will be described with reference to the flowcharts of FIGS.

[0077] (4-1) Master setting items The computer program 203 stored in the memory 113 of the PLC 111 stores a master table such as that shown in Table 1 in a non-volatile memory (not shown) provided in the memory 113.

[0078] [Table 1]

[0079] "Warning selection" is a setting item for determining which operation mode the CPU 112 should execute: a first operation mode that notifies the remaining length RL and the extension length EL, or a second operation mode that notifies the insertion length IL. If a warning is selected, execution of the first operation mode is specified, and if a warning is not selected, execution of the second operation mode is specified.

[0080] In the first operating mode, when the protruding length EL is displayed, a negative sign "-" is added to the dimension value, which serves as a warning when the forks 32 protrude from one side of the pallet P and the opposite side. A similar warning is also provided by changing the background color of the display when displaying the remaining length RL and when displaying the protruding length EL. This type of display mode is the reason for the name "warning selection."

[0081] In "Fork length (claw length)," the claw length L1 from the base 35R of the claw 35 to the tip 35E of the fork 32 of the forklift 11 to which the fork insertion amount management support device 101 is attached is set. This item sets the claw length L1, not the fork length L2. A length of 700 to 2000 mm can be set.

[0082] The "correction error" is set to an offset length L3. A length of 0 to 200 mm can be set. As shown in FIG. 7(A), when the claw length L1 and the fork length L2 are the same, the correction error is set to 0.

[0083] If the distance sensor 131 is thin and does not reach the thickness of the base 36 of the fork 32, the measurement surface 131a of the distance sensor 131 will be offset from the base 35R of the claw 35 to the side opposite the tip 35E. In this case, the offset length L3 must be a negative value. However, based on the assumption that such a situation is unlikely to occur in reality, the setting range of the correction error in this embodiment is set to 0 to 200 mm.

[0084] "Display unit" is a setting item for determining whether the unit of dimensions to be displayed on the display screen 104a is centimeters or millimeters.

[0085] The "display measurement range" is set to the distance from the measurement surface 131a of the distance sensor 131. The set distance is used to avoid the process of displaying a numerical value on the display device 104 when the distance measured by the distance sensor 131 exceeds the set distance. A distance of 700 to 2000 mm can be set.

[0086] The fork insertion amount management support device 101 is intended to be used in a one-to-one relationship with a forklift 11, although this is not necessarily required. Of course, it is possible to attach it to a different forklift 11 as needed, but if there are to be as many fork insertion amount management support devices 101 as there are forklifts 11, there is little need to use it in this way. This is an operation method that is used in rare cases, such as in emergencies.

[0087] Therefore, it is assumed that the settings in the master table are set to values ​​specific to the forklift 11 to which the fork insertion amount management support device 101 is attached. Of the settings in the master table, the fork length (length of the claw portion), correction error, and display measurement range are values ​​specific to each individual forklift 11. Please refer to Figures 6 and 7(A) and (B) for details about the fork length (length of the claw portion), correction error, and display measurement range.

[0088] As an example, assume that the fork 32 of the forklift 11 equipped with the fork insertion amount management support device 101 has a claw length L1 of 1330 mm and an offset length L3 of 30 mm. In this case, 1330 is entered as the fork length (claw length) in the master table, and 30 is entered as the correction error. Then, according to the above formula (2), the fork length L2 is 1300 mm, so 1300 is entered as the display measurement range. As the forklift 11 approaches the pallet P carrying the load B, the measured distance DL by the distance sensor 131, which initially exceeds 1300 mm, shortens. Until it falls below 1300 mm, the display is set not to display the dimension indicating the insertion state of the fork 32 relative to the pallet P. When the measured distance DL shortens to 1300 mm, the tip 35E of the fork 32 is positioned flush with one surface of the pallet P.

[0089] Among the settings in the master table, the presence or absence of warning selection and the display unit are not setting items specific to the forklift 11 equipped with the fork insertion amount management support device 101, but are determined by the preferences of the user, such as the operator of the forklift 11.

[0090] For example, when displaying the insertion status of the fork 32 into the pallet P, if you want to display the remaining length RL and the protruding length EL, you select "with warning selection," and if you want to display the insertion length IL, you select "without warning selection."

[0091] Regarding the display unit, a desired unit is set between centimeters and millimeters as the unit of the numerical values ​​of the dimensions to be displayed on the display screen 104a.

[0092] In view of the above-described circumstances, it is assumed that the master table will be operated in such a way that each item is set in advance.

[0093] (4-2) Processing procedure (a) Home screen As shown in the flowchart of FIG. 9, when the fork insertion amount management support device 101 is started up, the CPU 112 of the PLC 111 displays a home screen on the display screen 104a in accordance with the computer program 203 stored in the memory 113 (step S101).

[0094] The home screen displays a settings button, an operation button, and other buttons (not shown). The settings button is a button for instructing the setting of the pallet length PL of the pallet P that is about to be transported by the forklift 11. The operation button is a button for instructing the execution of fork insertion amount management support when the forklift 11 starts transporting the load B. The other buttons include, for example, a maintenance button for informing the start of resetting the master table shown in Table 1.

[0095] The CPU 112 waits for processing to determine in order whether a setting button has been designated (step S102), whether an operation button has been designated (step S103), and whether any other button has been designated (step S104).

[0096] (b) Pallet length setting When the CPU 112 determines that the setting button has been designated by tapping on the touch panel 105 (YES in step S102), it controls the driving of the display device 104 to display input instructions on the display screen 104a (step S105). The input instructions display an input field for inputting the value of the pallet length PL of the pallet P to be transported by the forklift 11, and an enter button.

[0097] A user of the fork insertion amount management support device 101, typically an operator of the forklift 11, inputs the value of the pallet length PL into the input field using the touch panel 105 and taps the enter button.

[0098] The CPU 112 then determines whether the pallet length PL has been input (YES in step S106), determines whether the user has indicated their intention to confirm (YES in step S107), and saves the input value of the pallet length PL in the memory 113 (step S108). As an example, the value of the pallet length PL is temporarily stored in a volatile memory such as a RAM in the memory 113.

[0099] The pallet length PL is referenced in the first operation mode (steps S110 to S112, see FIG. 10), but is not referenced in the second operation mode (steps S114 to S116, see FIG. 11). Therefore, when the second operation mode is selected, that is, when the warning selection in the master table (see Table 1) is set to "none," the CPU 112 does not allow the setting process of the pallet length PL (steps S102 to S108).

[0100] As a method for not allowing the setting process of the pallet length PL, when the warning selection is set to "none," for example, a method can be adopted in which the setting button is not displayed on the home screen or the setting button is disabled.

[0101] (c) Operation The operator, who starts the transporting work of the package B using the forklift 11, taps the operation button on the touch panel 105.

[0102] When the CPU 112 determines that the operation button has been selected (YES in step S103), it executes a fork insertion amount management support process (see step S109 onwards).

[0103] In the fork insertion amount management support process, a determination is made as to whether the first operation mode or the second operation mode should be executed (step S109). This determination is made according to whether or not a warning is selected in the master table. CPU 112 refers to the warning selection in the master table, and if it is set to "yes," executes the process of the first operation mode (steps S110-112, see FIG. 10), and if it is set to "no," executes the process of the second operation mode (steps S114-116, see FIG. 11).

[0104] (First operating mode) In the first operation mode, the CPU 112 refers to the sensor value of the distance sensor 131 (step S110) and executes distance calculation (step S111). The distance calculation is a process of finding the solution of the above equation (3), that is, PL-(L2-DL).

[0105] The value of the pallet length PL is the value stored in the memory 113 in step S108.

[0106] Fork length L2 is found by subtracting the correction error from the fork length (claw length) set in the master table shown in Table 1. Using the numerical values ​​from the specific example described above, claw length L1 is 1330 mm and offset length L3, which is the correction error, is 30 mm, so fork length L2 is calculated as 1300 mm.

[0107] The measured distance DL can be obtained by calculation processing of the CPU 112 based on the sensor value of the distance sensor 131.

[0108] When the CPU 112 obtains a solution to equation (3), it executes a display process (step S112). As shown in FIG. 10, the display process in the first operating mode begins with determining whether the display conditions are met (step S112-1). In this determination, the value of the display measurement range set in the master table is compared with the distance DL measured by the distance sensor 131, and it is interpreted that the display conditions are met when the measured distance DL reaches the value of the display measurement range. In actual practice, the display conditions are not met until the tip ends 35E of the forks 32 are flush with the insertion opening S of the pallet P (NO in step S112-1), and it is determined that the display conditions are met when they reach the same plane (YES in step S112-1).

[0109] The CPU 112 remains in standby mode until it determines that the display conditions are met (YES in step S112-1), and therefore the process of displaying the numerical value on the display screen 104a (step S112-4) is avoided until the tip 35E of the fork 32 reaches the same plane as the insertion port S of the pallet P.

[0110] If the CPU 112 determines that the display condition is met (YES in step S112-1), it refers to the solution of equation (3) obtained in step S111 and determines whether the value is 0 or greater, that is, whether the value is a positive value or 0 (step S112-2).

[0111] If the solution of equation (3) is 0 or greater, it means that the tips 35E of the forks 32 inserted into one side of the pallet P do not penetrate through the surface on the opposite side of the pallet P. In this case, the CPU 112 treats the solution of equation (3) as the remaining length RL (see FIG. 8(B)). As described above, the remaining length RL is the length from the tips 35E of the forks 32 inserted into one side of the pallet P until they reach the surface on the opposite side of the pallet P.

[0112] On the other hand, if the solution to equation (3) is not greater than 0, i.e., is a negative value, it means that the tip 35E of the fork 32 inserted into one side of the pallet P protrudes from the surface opposite to that side. In this case, the CPU 112 treats the solution to equation (3) as the protrusion length EL (see FIG. 8(D)). As described above, the protrusion length EL is the length by which the tip 35E of the fork 32 inserted into one side of the pallet P protrudes from the surface opposite to that side of the pallet P.

[0113] Therefore, the process of step S112-2 can be said to be a process of determining whether the numerical value to be displayed on the display screen 104a is the remaining length RL or the protruding length EL.

[0114] If the CPU 112 determines that the solution of equation (3) is greater than or equal to 0 (YES in step S112-2), it controls the background color displayed on the display screen 104a to green (step S112-3), treats the solution of equation (3) as the remaining length RL, and displays this dimension numerically on the display screen 104a (step S112-4).

[0115] If the CPU 112 determines that the solution of equation (3) is not greater than or equal to 0 (NO in step S112-2), it controls the background color displayed on the display screen 104a to red (step S112-5), treats the solution of equation (3) as the protrusion length EL, and displays this dimension as a numerical value on the display screen 104a (step S112-6).

[0116] The CPU 112 displays the remaining length RL without adding a positive or negative sign to the numerical value, and displays the extension length EL with a negative sign to the numerical value. Furthermore, the CPU 112 controls the background color to green when displaying the remaining distance sensor 131, and controls the background color to red when displaying the extension length EL. This allows the operator of the forklift 11 to distinguish whether the remaining length RL or the extension length EL is being displayed.

[0117] 12(A) to 12(D) are schematic diagrams showing examples of displaying the remaining length RL and the protruding length EL in the states of FIGS. 8(A) to 8(D). Fork length L2 = 1300mm Pallet length PL= 800mm Assume that:

[0118] Fig. 8(A) shows a state in which the tip 35E of the fork 32 has not yet reached one surface of the pallet P. In this case, as shown in Fig. 12(A), the process of step S112-1 avoids displaying the numerical value that is the solution of equation (3), and no numerical value is displayed on the display screen 104a.

[0119] Figure 8(B) shows a state in which the tips 35E of the forks 32 are inserted, for example, 430 mm into one surface of the pallet P. At this time, the solution to equation (3) executed in step S111 is +370, and the CPU 112 determines that the remaining length RL is 370 mm. Therefore, as shown in Figure 12(B), the CPU 112 displays 370 mm on the display screen 104a and indicates the remaining length RL numerically (step S112-4). The background color at this time is green.

[0120] Fig. 8(C) shows a state in which the tips 35E of the forks 32 have reached the surface opposite to one surface of the pallet P. At this time, the solution of equation (3) executed in step S111 is 0, and the CPU 112 determines that the remaining length RL is 0 mm. Therefore, as shown in Fig. 12(C), the CPU 112 displays 0 mm on the display screen 104a and indicates the remaining length RL numerically (step S112-4). The background color at this time is green.

[0121] Fig. 8(D) shows a state in which the tips 35E of the forks 32 protrude, for example, 80 mm from one surface of the pallet P and the opposite surface. In this case, the solution of equation (3) executed in step S111 is -80, and the CPU 112 determines that the protrusion length EL is 80 mm. Therefore, as shown in Fig. 12(D), the CPU 112 displays -80 mm on the display screen 104a and indicates the dimension of the protrusion length EL numerically (step S112-6). The background color at this time is red.

[0122] (Second operating mode) In the second operation mode, the CPU 112 refers to the sensor value of the distance sensor 131 (step S114) and executes distance calculation (step S115). The distance calculation is a process of finding the solution of the above equation (4), that is, L2-DL.

[0123] Fork length L2 is found by subtracting the correction error from the fork length (claw length) set in the master table shown in Table 1. Using the numerical values ​​from the specific example described above, claw length L1 is 1330 mm and offset length L3, which is the correction error, is 30 mm, so fork length L2 is calculated as 1300 mm.

[0124] The measured distance DL can be obtained by calculation processing of the CPU 112 based on the sensor value of the distance sensor 131.

[0125] When the CPU 112 obtains a solution to equation (4), it executes a display process (step S116). As shown in FIG. 11, the display process in the second operating mode begins with determining whether the display conditions are met (step S116-1). In this determination, the value of the display measurement range set in the master table is compared with the distance DL measured by the distance sensor 131, and it is interpreted that the display conditions are met when the measured distance DL reaches the value of the display measurement range. In actual practice, the display conditions are not met until the tip ends 35E of the forks 32 are flush with the insertion opening S of the pallet P (NO in step S116-1), and once they reach the same plane, it is determined that the display conditions are met (YES in step S116-1).

[0126] The CPU 112 remains in a standby state until it determines that the display conditions are met (YES in step S116-1), and therefore the process of displaying the numerical value on the display screen 104a (see step S116-3) is avoided until the tip 35E of the fork 32 reaches the same plane as the insertion port S of the pallet P.

[0127] When the CPU 112 determines that the display conditions are met (YES in step S116-1), it controls the background color displayed on the display screen 104a to green (step S116-2), and determines the solution of equation (4) as the insertion length IL and displays that dimension numerically on the display screen 104a (step S116-3).

[0128] 13(A) to 13(D) are schematic diagrams showing examples of displaying the insertion length IL in the states of FIGS. 8(A) to 8(D). Fork length L2 = 1300mm Pallet length PL= 800mm Assume that:

[0129] Fig. 8(A) shows a state in which the tip 35E of the fork 32 has not yet reached one surface of the pallet P. In this case, as shown in Fig. 13(A), the process of step S116-1 avoids displaying the numerical value that is the solution of equation (4), and no numerical value is displayed on the display screen 104a.

[0130] Figure 8(B) shows a state in which the tips 35E of the forks 32 are inserted, for example, 430 mm into one surface of the pallet P. In this case, the solution to equation (4) executed in step S115 is +430, and the CPU 112 determines that the insertion length IL is 430 mm. Therefore, as shown in Figure 13(B), the CPU 112 displays 430 mm on the display screen 104a and indicates the dimension of the insertion length IL numerically (step S116-3).

[0131] Figure 8(C) shows a state in which the tips 35E of the forks 32 have reached the surface opposite to one surface of the pallet P. At this time, the solution to equation (4) executed in step S115 is +800, and the CPU 112 determines that the insertion length IL is 800 mm. Therefore, as shown in Figure 13(C), the CPU 112 displays 800 mm on the display screen 104a and indicates the dimension of the insertion length IL numerically (step S116-3).

[0132] Fig. 8(D) shows a state in which the tips 35E of the forks 32 protrude, for example, 80 mm from one surface of the pallet P and the opposite surface. In this case, the solution to equation (4) executed in step S115 is +880, and the CPU 112 determines that the insertion length IL is 880 mm. Therefore, as shown in Fig. 13(D), the CPU 112 displays 880 mm on the display screen 104a and indicates the dimension of the insertion length IL numerically (step S116-3).

[0133] (End of processing) 9, after executing the display process (step S112 or step S116), the CPU 112 determines whether or not an end instruction has been given (step S113). The end instruction is given, for example, by making an end button (not shown) appear on the home screen (see step S101) displayed on the display screen 104a, detecting a tap on this end button using the touch panel 105, or by turning off the power to the device main body 102.

[0134] When the CPU 112 determines that an end instruction has been issued (YES in step S113), it executes memory clear (step S117) and ends the process. Memory clear is a process of erasing various data temporarily stored in a volatile memory such as a RAM in the memory 113, for example, data on the pallet length PL.

[0135] 3. Effects (1) Basic effects (1-1) Effect According to this embodiment, the computer program 203 stored in the memory 113 of the PLC 111 causes the CPU 112 to execute a process of calculating the remaining length RL, the protruding length EL, and the insertion length IL based on the value of the fork length L2, the value of the pallet length PL, and the measured distance DL by the distance sensor 131.

[0136] The CPU 112 subtracts the value of the measured distance DL from the value of the fork length L2 to calculate the insertion length IL of the fork 32 relative to the pallet P, and subtracts the value of the insertion length IL from the value of the pallet length PL to calculate the remaining length RL and the protruding length EL.

[0137] (1-2) Effects According to this embodiment, the remaining length RL and the protruding length EL can be displayed numerically on the display screen 104a, so that the operator of the forklift 11 can visually see the process of the forks 32 being inserted into the pallet P to an appropriate amount. This can contribute to optimizing the amount of insertion of the forks 32 into the pallet P.

[0138] (2) Minus sign According to this embodiment, the numerical value of the protrusion length EL is displayed as a negative value, so that the operator of the forklift 11 can be warned that the fork 32 inserted from one side of the pallet P has protruded through the opposite side of the pallet P.

[0139] (3) Background color According to this embodiment, the background color of the display screen 104a is changed when displaying the remaining length RL and when displaying the protruding length EL, so that this also warns the operator of the forklift 11 that the fork 32 inserted from one side of the pallet P has protruded through the side opposite to the one side of the pallet P.

[0140] (4) Prevention of unnecessary display According to this embodiment, when the measured distance DL exceeds a preset distance, the process of displaying the numerical value on the display device 104 is avoided, thereby preventing unnecessary numerical values ​​from being displayed on the display screen before the fork 32 is inserted into one side of the pallet P.

[0141] (5) Two operating modes According to this embodiment, it is possible to alternatively select between a first operating mode that displays the remaining length RL and the protruding length EL, and a second operating mode that displays the inserted length IL, so that it is possible to select the display format according to preference and situation, thereby promoting further optimization of the amount of insertion of the fork 32 into the pallet P.

[0142] (6) Distance sensor placement According to this embodiment, the distance sensor 131 is configured to be attached to the backrest 34 of the forklift 11, so that the deviation between the claw length L1 and the fork length L2 can be minimized.

[0143] (7) Display and input devices According to this embodiment, the display device 104 is configured to be attached to the front pillar 21 provided on the cab 16, and therefore good visibility can be obtained from the cab 16. In this case, if the display device 104 is equipped with a touch panel 105, good operability can be obtained in addition to good visibility.

[0144] (8) One package According to this embodiment, the display device 104 has the touch panel 105 integrated therein and the PLC 111 built in, so that the entire device can be made smaller and the portability can be improved.

[0145] 4. Variations Various modifications and variations are possible in practice.

[0146] For example, in this embodiment, an example of application to a counterbalance forklift 11 has been shown, but it may also be applied to a reach forklift.

[0147] In this embodiment, an example in which the PLC 111 is used as the control unit has been shown, but it is not essential to use the PLC 111, and the control unit may be configured by a general computer that operates under an OS.

[0148] Equations (1) to (4) are merely examples of equations for calculating the remaining length RL, the protruding length EL, and the inserted length IL. It goes without saying that modified equations (1) to (4) or completely different equations may be used as long as they can calculate the remaining length RL, the protruding length EL, and the inserted length IL.

[0149] Various modifications can also be made to the process for avoiding the display of a numerical value on the display device 104 when the forks 32 are not inserted into the pallet P. For example, the process for displaying a numerical value on the display device 104 may be avoided when the measured distance DL is less than the fork length L2. As another example, the process for displaying a numerical value on the display device 104 may be avoided when the insertion length IL is a negative value.

[0150] Any other variations and modifications are possible in the implementation. [Explanation of symbols]

[0151] 11. Forklift 12 Body 13 Drive wheels 14 Steering wheel 15 Handle 16 Driver's cab 17 sheets 18 Head Guard 19 Beam 20 Roof 21 Front pillar 31 Fork mechanism 32 Fork 33 Mast 34 Backrest 35 Claw 35E Tip 35R base 36 Base 37 Lift cylinder 38 Tilt cylinder 101 Fork insertion amount management support device 102 Device body 103 Housing 104 Display device 104a Display screen 105 Touch panel (input device) 111 PLC 112 CPU (arithmetic processing unit) 113 Memory (storage unit) 114 Input Interface 115 Output Interface 116 Power Supply Unit 131 Distance Sensor 131a Measuring surface 201 PC 202 Programming Support Tools 203 Computer Programs B. Luggage G ground surface P Palette S socket L1 Claw length L2 Fork length L3 offset length DL measurement distance EL protrusion length IL Insertion Length PL Pallet length RL remaining length

Claims

1. a distance sensor attached to a forklift that inserts forks into a pallet carrying a load and transports the load together with the pallet, the distance sensor detecting the distance between the pallet and the fork in the inserting / removing direction; an input device that accepts input of information; a display device attached to a position visible from the driver's cab of the forklift; a storage unit that stores the length of the pallet along the insertion / removal direction as a pallet length; a calculation processing unit that calculates the remaining length of the tips of the forks inserted into one side of the pallet until they reach the surface opposite to the one side of the pallet and the protruding length from the surface opposite to the one side, based on the value of the fork length from the measurement surface of the distance sensor to the tips of the forks, the value of the pallet length stored in the memory unit, and the distance measured by the distance sensor; Equipped with The arithmetic processing unit an input control for storing the pallet length input to the input device in the storage unit; a display control for displaying the remaining length and the protruding length as numerical values ​​on the display device; A fork insertion amount management support device that performs the above.

2. The arithmetic processing unit a process of subtracting the measured distance value from the fork length value to calculate an insertion length of the fork relative to the pallet; a process of subtracting the value of the insertion length from the value of the pallet length to calculate the remaining length and the protruding length; To execute The fork insertion amount management support device according to claim 1.

3. The calculation processing unit displays the numerical value of the protrusion length in a negative value. The fork insertion amount management support device according to claim 1.

4. the calculation processing unit changes the background color of the display screen when displaying the remaining length and when displaying the protruding length. The fork insertion amount management support device according to claim 3.

5. the calculation processing unit avoids a process of displaying a numerical value on the display device when the measured distance exceeds a preset distance. The fork insertion amount management support device according to claim 1.

6. The arithmetic processing unit A process of calculating the remaining length and the protruding length is executed as a first operation mode; a second operation mode in which the value of the measured distance is subtracted from the value of the fork length to calculate an insertion length of the fork relative to the pallet; enabling the input device to alternatively select between the first operation mode and the second operation mode; executes one of the first operation mode and the second operation mode selected by the input device; The fork insertion amount management support device according to claim 1.

7. The distance sensor is configured to be attached to a backrest of the forklift. The fork insertion amount management support device according to claim 1.

8. The display device is configured to be attached to a front pillar provided in the driver's cab. The fork insertion amount management support device according to claim 1.

9. the display device is a touch panel display device having the input device on a display screen, The fork insertion amount management support device according to claim 1.

10. the display device integrally includes the input device, the storage unit, and the arithmetic processing unit; The fork insertion amount management support device according to claim 1.

11. A forklift that inserts forks into a pallet carrying a load and transports the load together with the pallet, A fork insertion amount management support device according to any one of claims 1 to 10 is provided. forklift.

12. The fork insertion amount management support device is attached to a forklift that inserts forks into a pallet carrying a load and transports the load together with the pallet. The fork insertion amount management support device is loaded into a computer that includes the fork insertion amount management support device. a function of storing the length of the pallet along the insertion / removal direction of the forks as a pallet length in a storage unit in response to an input from an input device; a function of calculating the remaining length of the tips of the forks inserted into one side of the pallet until they reach the surface of the pallet opposite to the one side, and the protruding length from the opposite surface, based on the value of the fork length from the measurement surface of a distance sensor that detects the distance between the forks and the pallet in the insertion / removal direction, the value of the pallet length stored in the memory unit, and the distance measured by the distance sensor; a function of displaying the remaining length and the protruding length on a display device attached to a position visible from the driver's seat of the forklift; A computer program that executes

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